THE CONCRETE BRIDGE MAGAZINE

SUMMER 2013

ASPIRE is a quarterly magazine published by PCI in cooperation with the associations of the National Concrete Bridge Council. The editorial content focuses on the latest technology and key issues in the Concrete Bridge Industry.

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A E S T H E T I C S C O M M E N T A R Y by Frederick Gottemoeller Airport-terminal roadways are hybrids; they are not quite buildings, but they are not quite bridges either. Design speeds for these structures are low, permitted curvatures are sharp, and long spans are not required to cross ramps below. The pier spacing for these structures mimics the bay sizes of the terminal itself. In fact, for reasons of architectural or functional harmony, it may well be neces- sary for the two dimensions to match. Like a building, the terminal roadway is seen close-up by pedestrians. For those on the lower arrival level, the space below the terminal roadway becomes an extension of the arrivals hall, which is often flled with people. The terminal roadway defnes the boundaries and creates the ceiling of this huge outdoor space. If done well, the roadway structure can make the arrival experience more welcoming. This is an immense challenge. The curves of the roadway and the need to clear undercrossing ramps necessitates multiple pier confgurations and straddle bents. The key to success in this situation is to use simple, attractive details, which are consistently repeated. The Maynard H. Jackson Jr. International Terminal Elevated Roadway System does this very well. The piers always use "inverted T" pier caps supported by simple square columns. The pier caps always end with rectangular blocks, terminating the cap and at the same time disguising the "T" cross section. At the straddle bents, the rectangular end blocks are always simple extensions of the columns. The differing planes of the webs and fanges of the precast con- crete I-girders create panels of shade and shadow that add to the visual interest. With a highway bridge, these characteristics are seen from such a distance and at such high speed that they are barely noticed. Here, they become valuable contributors to the overall impression. The fact that there are no decorative architectural features adds to the effect of simplicity and calm. Adding such features would have added only visual distraction and complication. The simplicity and calm extends to the roadway lighting and the way it is supported by the structure. Finally, the light-colored coating evens out the color and texture of the concrete elements and makes it possible to appreciate the piers as simple shapes. It also refects light within this huge arrival hall, making it brighter in daylight and easier to light at night. For any airport terminal seen from the landside, the terminal roadway structure is more important in determining the architectural impression of the terminal than the terminal building itself. Many airports miss this fact, spending much time and energy on the architecture of the building and not enough on the appearance of the terminal roadway. By constructing a terminal roadway of this high visual quality, Atlanta has avoided this trap. ASPIRE , Summer 2013 | 17 Book_Sum13.indb 17 7/1/13 6:57 AM

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